1. Field of the Invention
This invention relates to a method of manufacturing a thin ribbon wafer of semiconductor material comprising preparing a material consisting essentially of pure silicon or silicon with less than 10 atomic % of at least one additional element selected from the group consisting of hydrogen, phosphorus, sulfur, oxygen, boron, arsenic, tellurium, tin, selenium, aluminum, gallium, indium, chromium, silver, iron and bismuth; by heating said semiconductor material to a melt; ejecting said melt through a nozzle under a pressure from 0.01 to 1.5 atm. onto a moving surface of a cooling substrate to cool said melt at a cooling rate of 10.sup.3 -10.sup.6 .degree.C./sec; forming a thin ribbon wafer of semiconductor material by separating it from said moving surface of cooling substrate; whereby the thus obtained thin ribbon wafer of semiconductor material has a polycrystalline structure composed of more than 50% of a grain having grain size of more than 5 .mu.m, a thickness of 5-200 .mu.m, a sufficient flexibility and is composed of at least two different type semiconductor materials selected from p-type, i-type and n-type.
2. Description of the Prior Art
The largest problem of semiconductor material in this field of science is how to mass produce thin ribbon wafers of silicon semiconductor less expensively while producing wafers having different substrates having different uses, such as in several semiconductor devices such as in solar cells, photoelectric transducers, etc. In the prior art, it is known that a thin ribbon wafer of single crystal silicon can be manufactured by an EFG method (edge-defined film-fed growth method), a lateral traction method, a capillary shaping method (capillary action shaping technique), an inverted Stepanov growth method, or a laser zone crystallization method for ribbon type crystal. It is also known that a thin sheet of silicon semiconductor in crystal form can be produced by a dip-coating method, a CVD method (chemical vapor deposition growth method), a CVD floating substrate growth method, or a hot-forming method for silicon, etc.
However, these methods are slower than that of the present invention, in the order of 10.sup.2 -10.sup.3, in the time of manufacturing a thin ribbon wafer. As the result, in terms of necessary electric power used in said production of a thin ribbon wafer of semiconductor, prior art methods were 10.sup.2 -10.sup.3 times more expensive.
Also the thus obtained prior art products were very brittle in the bending test and liable to be broken as compared with the present invention, and their workability for use as an electron device were consequently below the standards of the present invention.